Field of the Invention
The present application relates to the art of a control system for a transmission adapted to establish a predetermined gear stage by bringing into engagement a first engagement device for transmitting torque and a second transmission whose torque transmitting capacity is variable.
Discussion of the Related Art
JP-A-2013-151997 describes a transmission having three frictional clutches and three dog clutches. A gear stage of the transmission taught by JP-A-2013-151997 can be shifted among first to eighth forward stages and a reverse stage by selectively bringing into engagement three clutches. However, the dog clutch has to be brought into engagement while synchronizing rotational speeds between an input member and an output member, and this may slow the response of shifting operation of the gear stage. According to the teachings of JP-A-2013-151997, therefore, a common dog clutch is brought into engagement to establish gear stages next to each other to reduce opportunities of speed synchronization.
JP-A-2014-105845 describes a claw clutch in which engagement teeth of rotary members are brought into engagement by pushing one of the rotary members. According to the teachings of JP-A-2014-105845, those engagement teeth of rotary members may be engaged with each other even if the rotational speeds of the rotary members are not in complete synchronization. To this end, in the claw clutch, each engagement tooth has a chamfered leading end.
In the transmission taught by JP-A-2013-151997, response of the shifting operation of the gear stage may be improved by applying the chamfered leading end of the engaging tooth taught by JP-A-2014-105845. In this case, however, friction between the teeth being engaged to each other will be increased during engagement if rotational speeds of the rotary members are not in synchronization. In addition, torque transmitting capacity of the dog clutch cannot be changed gradually, and hence rotational speed of one of the rotary members would be changed abruptly to cause an engagement shock when bringing into engagement the teeth of the rotary members rotating at different speeds.